ULTRAVIOLET OBSERVATIONS OF THE LONG-PERIOD DWARF NOVA DX AND IN OUTBURST

Ultraviolet observations of the little-studied dwarf nova, DX And, are presented. The observations were made with the International Ultraviolet Explorer satellite (IUE) during the late stages of a rise to outburst maximum in 1989 November. The spectra indicate a low orbital inclination angle and show clear signs of substantial interstellar reddening [E(B-V) = 0.20 +/- 0.04]. The wind-dominated N v lambda-1240 and C IV lambda-1549 profiles show significant velocity-shifting within our time series of spectra. If these motions are linked with the binary orbit, an estimate of 11 hr is obtained for the orbital period. Fitting of the C IV and N V absorption profiles provides a lower limit to the mass loss rate of a few times 10(-11) M. yr-1. It is argued that the ionization state of DX And's wind is most probably higher than usual or, failing that, the nitrogen abundance in the accreting material is enhanced.